Tadka means to Fry something (some aromatic vegetables) in oil, butter or ghee and add that to something which does not have taste of its own.
Chaunk in Hindi, but also called tarka, tadka, bagar, phoron, or phoran or popu. It is a garnish and/or cooking technique used in the cuisines of India, Bangladesh, and Pakistan, in which whole spices such as minced ginger, green chillies, curry leaves are fried in oil or ghee to get their flavors into a dish.
Chhaunk is added at the end of cooking, just before serving a dal, sambar or stew, or else prepared at the beginning of cooking, before adding the ingredients to a curry or similar dish.Chaunk is believed to not only add flavor but also to aid in digestion.
Tadka is a tempering is a process used for flavoring certain dishes. To temper a dish, oil is heated and spices added to it and fried. This spice flavoured oil is then added to the dish as a final touch.
In Nepali it is jhaneko, jhannu , in Hindi it is popularly called a chhaunk, tarka, tadka (तड़का), bagar (बगार) like on Dal tadka. In Punjabi it is known as tarka, Gujarati its vaghar (વઘાર), Bengali is bagar , bagar dewa or phoron , in Tamil thaalithal , in Kannada it is oggaraṇe, Telugu it is popu , thiragamaatha , taalimpu , Marathi called phodani , pholni , Urdu it is tarka , Baghar also called "vaghar" in Gujarati and in Konkani it is Phonna. Tadka is the north Indian style of garnishing curries with fried onions and garlic.